I have a 1985 evinrude 140. The engine will run okay out of water, but after idling for several minutes engine loads up with fuel and shuts off. When in the water engine will idle in Neutral, for a short time before loading up with fuel and shutting off, will not idle in gear at all. You have to rev it up and slam it in gear and gas it to keep it from dying. I premix the fuel and oil. Engine runs fine at WOT and mid throttle just a problem with idling. What would be the first thing to look for and check.? I have tried adjusting idle screw but it doesn't really help. Thanks in advance for any input.